As many as 80,000 bee colonies have died or been damaged this year after pollinating almond trees in the San Joaquin Valley, and some beekeepers are pointing to pesticides used on almond orchards as a possible cause.
The damaged colonies are the latest worry in the beekeeping community, which is struggling to deal with colony collapse disorder, a phenomenon in which beekeepers open hives after pollination and find them empty, with the bees nowhere to be found.
The damaged hives are a significant agricultural issue. Ninety percent of honeybees that pollinate crops in the United States are used during the California almond bloom. And there is a cascading effect. Bees used to pollinate almond trees typically are moved to pollinate other crops, such as apples, cranberries, cherries and watermelons.
It’s not clear why the damaged hives are showing up this year, as opposed to prior years.
“We’re a little mystified,” said John Miller, a beekeeper based in Newcastle, about 40 miles northeast of Sacramento. “We have some colonies that looked like they’ve been through some kind of brood die-off. It’s puzzling because it is intermittent and random.”
Miller keeps about 12,000 colonies of bees, which pollinate trees at almond farms in Newcastle. He said the damage he has incurred is moderate compared with what he has seen other beekeepers suffer – whole colonies damaged or dead.
Almond pollination in California requires the use of 1.6 million bee colonies, almost all brought in from other states by an army of 1,300 commercial beekeepers.
Damage to the hives this spring was so pronounced that it forced an impromptu meeting March 24 in Los Banos between beekeepers and the U.S. Environmental Protection Agency. In that meeting, 75 beekeepers weighed in and said three-quarters of their hives showed damage. That equals nearly 80,000 damaged hives, said Michele Colopy, program director with the Pollinator Stewardship Council, an advocacy group for beekeepers.
At the meeting of beekeepers, bee brokers and managers from the EPA’s Office of Pesticide Programs, the practice of almond growers engaging in “tank mixing” of insecticides was raised as a major issue, Colopy said.
Almond growers typically apply one or a mix of pesticides that can include clothianidin, dinotefuran, imidacloprid and thiamethoxam and now apply two new products, tolfenpyrad and cyantraniliprole, Colopy said.
She suggested that mixing certain insecticides is to blame for the damage to hives, along with the practice of applying insecticides during the early daytime hours when bees are foraging.
Almond growers are not required to apply insecticides and fungicides at any particular time.
“Our best practices recommend almond growers avoid application of insecticides during bloom and minimize exposure to bees and pollen,” said Bob Curtis, associate director of agricultural affairs with the Almond Board of California.
The board’s recommendations include spraying at midafternoon and in the evening, Curtis said.
Los Banos beekeeper Gene Brandi said the pesticides used by growers do not have explicit label warnings about their possible effects on bees. The EPA assessed their toxicity, but only to adult bees, and found them to be nontoxic.
“Nonetheless, these chemicals affect the bee colony by affecting the brood,” Brandi said, adding, “The damaged hives are a significant number and enough to cause alarm.”
Liz Purchia, an EPA spokeswoman, said the agency “understands the concerns of the beekeepers and growers and will continue to work with them.”
“There are general instructions on pesticide labels regarding tank mixing,” Purchia said. “However, EPA does not currently require any specific language for tank mixing fungicides for use on almond farms.”
Instructions on labels only direct farmers to follow the most restrictive instructions for any chemical and advise against mixing products whose labels prohibit tank mixing.
Purchia said the EPA is considering improvements in pollinator protection language to reduce the risk that bees face from pesticides applied during the almond bloom.
State pesticide agencies may require additional label instructions for tank mixing of pesticides within their jurisdictions, Purchia said.
In California, the state Department of Pesticide Regulation oversees the use and regulation of pesticides. “The department is working with beekeepers to look into the issue,” said spokeswoman Charlotte Fadipe. “However, there is no specific rule prohibiting tank mixes, unless the pesticide label states such.”
Beekeepers want language added to labels that warns of possible effects to bees of tank mixing, as well as an effort to end daytime applications of the insecticides. But, despite the evidence of bee colony damage, beekeepers don’t have scientific data linking the colony damage to tank mixing.
The pesticides and fungicides used on almond farms affect colonies most by contaminating the brood. This happens when bees bring pollen laden with insecticides back into the hive, said Denise Qualls, a bee pollination broker based in Danville.
“I think this is happening to everybody; it’s just that some people are paying more attention to it than other people are,” Qualls said. “Some get the hives back and see 10 percent loss and they just move on. But for some of these beekeepers, a 10 percent loss can be 600 hives. That’s a lot,” she said.
This year, Qualls saw a 10 percent damage rate among the 9,000 colonies she brokered and placed on almond farms for pollinating.
The price tag for replacing that many bees: $180,000.